• Magnetic fields from current sources.

Pre-requisite skills:  Basic vector algebra, understanding of the Biot-Savart law.

Approximate completion time:  Under an hour.

Provide sufficient detail to verify that the assignment was completed in a meaningful manner.

Applet by John Belcher

1.  In the applet, click on the "Reverse Velocity" button until the left-side current is flowing towards you (out of the plane of the computer screen) and the right-side current is flowing away from you (into the plane of the computer screen).   Make sure that the ratio of velocities is set to 1.

(a) Describe each of the vectors appearing on the screen.  (In other words, what does the blue vector represent, and so on?)

(b) Is there a region between the two wires where the total magnetic field is 0?    Why or why not?  (Hint:  Consider the right-hand rule.)

(c)   Suppose we define D as the distance between the two wires.   Consider a line in space that runs from one wire to the other.  Along this line, does the total magnetic field increase, decrease, or stay constant in value as you get nearer to one of the wires?   To answer, consider a point along this line a distance x = A from the left-side wire. Calculate the total magnetic field between the two wires as a function of A.

2. Repeat the three questions above for the case where both currents are traveling in the same direction.

Helpful Resources

The Biot-Savart Law by Fu Kwun Hwang.

Biot-Savart Law Applications by Carl R. (Rod) Nave.

Biot-Savart and Ampere's Laws by H. F. Cheung

Magnetic Fields by Angel Franco Garcia.

Loi de Biot-Savard (Biot-Savart) Law by Sibastien Bilodeau

P10D - Electricity and Magnetism by Janak Sodha

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